When soft tissue such as a ligament or a tendon becomes detached from a bone, surgery is usually required to reattach or reconstruct the tissue. Often, a tissue graft is attached to the bone to facilitate re-growth and permanent attachment. Various fixation devices, including sutures, screws, staples, wedges, and plugs have been used in the past to secure soft tissue to bone. For example, in typical interference screw fixation, the graft is fixed to the bone by driving the screw into a blind hole or a tunnel in the bone while trapping the end of the graft between the screw and the bone tunnel. In other methods, the graft is simply pinned against the bone using staples or sutures tied around the end of the graft to the bone.
U.S. Application Publ. No. 2008/0208253, the disclosure of which is incorporated by reference herein, discloses a surgical technique and associated instruments for securing soft tissue to bone which does not require the surgeon to tie suture knots to secure the tissue to the bone. According to this technique, a cannulated plug or screw is pre-loaded onto a distal end of a cannulated driver provided with an eyelet implant at its distal end. A suture attached to the graft is passed through the eyelet of the implant located at the distal end of the driver. The distal end of the driver together with the eyelet implant is inserted into bone (if the implant is self-punching) or is inserted into the bottom of a pre-formed hole, with the screw or plug disposed just outside the hole. Tension is applied to the suture to position the graft at the desired location relative to the bone hole. The screw or plug is then fully advanced into the pilot hole by turning the interference screw or tapping the plug until the cannulated screw or plug securely engages and locks in the eyelet implant, so that the cannulated plug or screw with the engaged eyelet implant is flush with the bone.
U.S. Application Publication No. 2008/0004659, the disclosure of which is incorporated by reference herein, discloses a technique and device for knotless fixation of tissue using a swivel anchor. According to this technique, a swivel anchor having a rotatable forked anchor tip is used to capture suture for surgical tissue repair without requiring suture knots. Tension on the repair constructs is adjustable through the selection of a specific chain link or links of the suture chain captured by a forked anchor tip of the swivel anchor. The swivel anchor is secured in a hole in bone by advancing a fixation device, such as a cannulated interference screw, over the body of the anchor.
Although the above-described techniques provide improved methods of graft fixation to bone through knotless fixation, it is not evident how to accomplish in situ surgical refinements such as getting a hard stop on a suture without relying on friction. Accordingly, there is a need in the art for improved technology for knotless tissue fixation.